单项选择题

There are no boot system commands in a router configuration in NVRAM.What is the fall back sequence that router will use to find an ios during reload?()

A.Flash,TFTPserver,ROM
B.Flash,NVRAM,ROM
C.ROM,NVRAM,TFTPserver
D.NVRAM,TFTPserver,ROM
E.TFTPserver,Flash,NVRAM